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Milk and dairy products are high-value foods; however, consumers suffering from lactose intolerance are not able to enjoy the nutritional benefi ts of these commodities. There are more and more researches and developments focusing on lowering the lactose content of milk and dairy foods in order to make them available for lactose intolerant people. In this study, we examined the coagulation time, product quality, texture profi le properties, and syneresis of yoghurts prepared from lactose-free milk. Signifi cant differences were observed between the control and lactose-free milks with respect to coagulation time and texture profi le. The fi rst rupture time, the hardness, and the adhesion force of the lactose-free yoghurt were higher compared to the control product. We observed remarkable difference between the whey leakage of control and lactose free yoghurt samples (21.47% and 14.63%). Results coming from instrumental texture profi le analyses showed that the preliminary lactose hydrolysis of milk resulted a fi rmer texture. It was confi rmed by the results of sensory evaluation, and considering the texture and taste, there was signifi cant difference between the control and lactose-free yoghurts.

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There is no standard limit value for somatic cell count (SCC) of raw goat milk in the EU despite that excellent hygienic quality milk is needed for the manufacture of fermented milk products or cheese varieties. Mastitis often results such high SCC - besides the potential risk for humans - that the clotting of milk will not be perfect, resulting slack curd with higher whey releasing; furthermore, wrong structure, ripening, bad sensory properties of cheese can also be its consequences. In this paper, we report the SCC of milk samples from five different goat breeds bred in Hungary, measured with two fast methods compared with the results from the reference method. Furthermore, we investigated the applicability and the accuracy of the MT-02 (Agro Legato Ltd., Hungary) instrument. We determined that the White Side test and the instrument MT were suitable for the estimation of possible risks and consequences in the case of the use of high SCC milk before production. The general summarized average milk SCC was 6.64 × 105 ml−1. The highest difference between the results from MT-02 and the fluorometric (reference) method was 5 × 105 ml−1, but it was a singular, extreme value. The r2 of the calculated linear calibration equation was 0.7819; consequently, this method seems to be applicable in the measurement of SCC with MT-02 instrument. Furthermore, the SCC of samples did not differ significantly by genotypes and by seasons (spring: 5.85 × 105 ml−1, autumn: 6.22 × 105 ml−1).

In this study the performance of a vibratory shear-enhanced processing system (VSEP) for the concentration of cheese whey was assessed and compared with a classical, cross-flow, plate and frame membrane configuration system (3DTA) with the same membrane (i.e. a C30F UF regenerated cellulose UF membrane with a 30 kDa molecular weight cutoff). The temperature and pressure dependences of the permeate flux, the permeate flux reduction ratio, the resistances and the rejection values were investigated. Comparison of the two systems revealed a definite advantage for the VSEP system equipped with the same membrane and operated at the same pressure and temperature. The VSEP system yielded a permeate protein retention of 99.7% vs. 74.5% for the 3DTA system, together with a higher average flux: 54 L m −2 h −1 vs. 44.2 L m −2 h −1 . The flux reduction ratio ( J/J0 ) was 0.60 vs. 0.42, and the total resistances 2.87*10 +13 m −1 vs. 4.54*10 +13 m −1 for the VSEP and 3DTA system, respectively.

The main goal of our work was to examine the possibility of using membrane separation to concentrate sweet whey, which could then be used as the basis of more products (e.g., ice cream, soft drinks containing whey).Whey from cheese making was concentrated by nanofiltration. The operating parameters were determined in permeate recirculation mode, and the concentration experiment was carried out under optimal conditions. The analytical assay of the permeate and concentrate such as total soluble solid content (TSS), protein content, and lactose content was determined using infrared measurements. The retention of lactose was over 95% up to 3.0 volume concentration ratio (VCR) at 20-bar transmembrane pressure. The analysis of the process was based on the resistance in series model and the van't Hoff law. The model parameters were determined on the basis of lactose content, assuming that lactose is the key component of whey. The values of these parameters are the concentration polarization (β=1.68) and total resistance (R TOT =1.60×10 14 m −1 ). The procedure was also repeated based on TSS, and the value of the total resistance was almost the same (R TOT = 1.59×10 14 m −1 ). Due to this, the applied models describe appropriately the batch membrane concentration process of whey. The lactose concentration can be used for the calculation instead of TSS, which simplifies the job of estimating the model parameters. Nomenclature β concentration polarization index [-] η viscosity of permeate [Pas] Δπ osmotic pressure difference [bar, Pa] A membrane area [m 2 ] b proportional coefficient [-] c M concentration in the polarization layer in the retentate [%, mol/m 3 ] c P concentration in the permeate [%, mol/m 3 ] c R concentration in the bulk in the retentate [%, mol/m 3 ] c R,lactose lactose concentration in the retentate [%, mol/m 3 ] c R,TSS total soluble solid concentration in the retentate [%] J permeate flux [m 3 /(m 2 s), L/(m 2 h)] J W pure water flux [m 3 /(m 2 s), L/(m 2 h)] J W,F pure water flux of fouled membrane [m 3 /(m 2 s), L/(m 2 h)] Δp TM transmembrane pressure [bar, Pa] R gas constant [J/(mol K)] Re Reynolds number [-] Ret retention of a given solute [%] R F fouling resistance [m −1 ] R F,end fouling resistance at the end of concentration [m −1 ] R M membrane resistance [m −1 ] R P resistance of polarization layer [m −1 ] R TOT total resistance [m −1 ] t time [s, h] T temperature [°C, K] V 0 initial volume of whey [m 3 ] V P volume of permeate [m 3 ] VCR volume concentration ratio [-]

Designing turbulence promoters with optimal geometry and using them for ultrafiltration systems has been a key challenge in mitigating membrane fouling. In this study, six different turbulence promoters were created using three-dimensional printing technology and applied in dead-end ultrafiltration. Three-dimensional-printed (3DP) turbulence promoter configurations were integrated into a classical batch ultrafiltration cell. The effects of these configurations and the stirring speeds on the permeate filtration flux, organic rejections, and membrane resistances were investigated. The fouling control efficiency of the 3DP promoters was evaluated using two polyethersulfone membranes in a stirred ultrafiltration cell with model dairy wastewater. The Hermia and resistance-in-series models were studied to further investigate the membrane fouling mechanism. Of the Hermia models, the cake layer model best described the fouling in this membrane filtration system. It can be concluded that the 3DP turbulence promoters, combined with intense mechanical stirring, show great promise in terms of permeate flux enhancement and membrane fouling mitigation. Using a well-designed 3DP turbulence promoter improves the hydrodynamic flow conditions on the surface of the stirred membrane separation cells based on computational fluid dynamics modeling. Therefore, the factors effecting the fabrication of 3DP turbulence promoters are important, and further research should be devoted to revealing them.

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